Recently, a deicer provided on a windshield of a motor vehicle or a rear window thereof requires a high amount of electric power to melt frozen ice or snow on the windshield or the rear window.
The output voltage of an alternator becomes a high voltage which is converted by a voltage converter. The high voltage is supplied to a deicer. This system is disclosed in the Japanese Laid Open No. 63-68444.
In the above-mentioned prior art, however, since a rectifier of the alternator is always connected to a battery, the output voltage of the alternator is maintained at 14.5[V].
Accordingly, as shown in FIG. 2, the output electric power of the alternator is not greatly; increased, even if a rotating speed of the alternator is increased.
Since the alternator requires a high electric power of as much as 1500 W to operate the electric conductor, however, a capacity of the alternator must be larger to generate the high electric power.